This invention relates to polymers and articles prepared from such polymers having permanently bonded to their surface a biocidal agent, processes for making such polymers and methods of use thereof.
Many attempts have been made to functionalize the surface of polymeric articles and for many reasons. The polymeric articles so functionalized have taken many forms such as beads, fibers, or film. In many instances the object of functionalization of the polymer was to provide the articles with biocidal properties. One of the applications for the functionalized polymers is to disinfect water in substitution of chlorine. One attempt to provide such materials is found in U.S. Pat. No. 4,349,646 to Nudel et al. This patent describes a water disinfectant formed from the reaction between a chloromethylated polystyrene or methacrylate and a tertiary amine. A quaternary salt is provided which is taught to be immobilized on the polymer resin carrier. However, in use it has been found that the material is not hydrolytically stable with the result that the quaternary salt leaves the polymer and becomes dissolved in the water.
Another active area of research is the attempt to provide textile fibers with biocidal properties. A recent attempt is described in U.S. Pat. No. 4,663,365 to Reinehr et al. This patent follows others wherein biocidally-active material is incorporated into the spin melt or spin composition employed to make the fiber thereby dispersing the biocidal agent throughout the bulk of the fiber. While some of the biocidal material will be close enough to the surface of the fiber to effect biocidal activity, a large portion of the biocidal material employed is effectively lost because of its being buried in the bulk of the fiber and thereby being separated from the microbes desirably destroyed.
Water purifying devices are being developed because of the concern for pure water available at remote locations. Such a device is described in U.S. Pat. No. 4,298,475 to Gartner wherein a column is fitted with suitable closures on each end and loaded with bactericidal medium such as iodinated cation exchange resin capable of disinfecting the water contained in the column. The biocidal agent is slowly released into the water.
Because cellulose is extensively used in clothing, numerous publications disclose means for modifying the polymer to affect its properties. Cellulosic fabrics have been treated to provide properties such as ion exchange, anti-stat properties, softening and dyeability. A typical disclosure is U.S. Pat. No. 905,200, filed Sept. 9, 1986 and published April 15, 1987 wherein cellulose fabrics are prepared by treatment with solutions of cross-linking agents, acid catalysts and quaternary. amine salts. The anti-microbial properties of grafted cellulose polymers were investigated by N. V. Kolokolkina et al and reported in Zh. Prikl. Khim, 58 (7), pgs. 1603-1606. However, these workers concluded that the lack of anti-microbial activity of the graft polymer was due to the covalent bonds between the cellulose and the grafted polyelectrolyte which prevented diffussion of the polyelectrolyte from the fibrous material to the microbial environment. Labile bonds were suggested.
Contrary to the Kolokolkina et al publication others have provided cellulose derivatives such as hydroxyethyl cellulose with bactericidal properties by grafting copolymer material such as 4-vinylpyridine to provide copolymers wherein the vinylpyridine is quaternized with ethyl bromide. Such a process is disclosed in European Patent Application 42075 published June 18, 1980. Anti-bacterial effectiveness of the compounds was demonstrated in vitro. Cellulosic fibers have been modified using linking units which are generally ether linkages although carbon-carbon covalent bonding and nitrogen linking units are also known. Bridging units are generally low molecular weight polyethers such as ethyoxylates but low molecular weights alkalene groups of up to about 3 carbon atoms are also known.
While attempts have been made in the past to functionalize the surface of polymers particularly to provide such surfaces with biocidal activity, a common problem has been the stability of the biocidal agent on the polymer. The attachment of biocidal material to the polymer substrate has been found to be unstable under usual hydrolytic conditions of use causing the material to be released into the liquid media. While it may not present danger since the biocidal materials most commonly employed are relatively safe for limited exposure at low concentration, the surface of the polymer becomes increasingly inactive because of the removal of the biocidal material. There is desired a hydrolytically stable, surface functionalized polymer which may be employed for long periods of time while retaining biocidal activity with a high degree of safety.